/**
 * 
 */
package com.onstar.cn.map.util;

import com.onstar.cn.map.common.Constants;
import com.onstar.cn.map.common.PoiItemInfo;

/**
 * @author Qiying Gong
 * 
 * @Created Feb 6, 2013
 */
public class DistanceCalculation {
	private static double EARTH_RADIUS = 6378.137;

	private static double rad(double d) {
		return d * Math.PI / 180.0;
	}

	public static double calculateDistance(double lon1, double lat1, double lon2,
			double lat2) {

		double radLat1 = rad(lat1);
		double radLat2 = rad(lat2);
		double a = radLat1 - radLat2;
		double b = rad(lon1) - rad(lon2);

		double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
				+ Math.cos(radLat1) * Math.cos(radLat2)
				* Math.pow(Math.sin(b / 2), 2)));
		s = s * EARTH_RADIUS*1000.0;
		s = Math.round(s * 10000) / 10000;

		return s;
	}

	public static boolean isSamePoint(PoiItemInfo itemInfo1, PoiItemInfo itemInfo2) {
		if (itemInfo1 == null || itemInfo2 == null) {
			return false;
		}
		double x1 = itemInfo1.getLongitude();
		double y1 = itemInfo1.getLatitude();
		double x2 = itemInfo2.getLongitude();
		double y2 = itemInfo2.getLatitude();

		return calculateDistance(x1, y1, x2, y2) < Constants.MIN_ROUTE_Distance;

	}
}
